🛡️ Sentinel: [CRITICAL] Fix arbitrary code execution vulnerability in AST evaluation

[bashandbone]

🚨 Severity: CRITICAL
💡 Vulnerability: The type validation logic using ast.parse(type_str, mode="eval") allowed generic ast.Call nodes to pass. Even though standard Python literal types were blocked, any accessible callable within the execution environment's scope could be arbitrarily executed, leading to a critical Arbitrary Code Execution (ACE) vulnerability during type resolution.
🎯 Impact: An attacker could potentially inject unvalidated configuration strings into the dependency container to achieve arbitrary code execution.
🔧 Fix: Explicitly restrict allowed callables in the TypeValidator to a predefined whitelist instead of broadly allowing the ast.Call class. Implemented rigorous AST node visitation checks that explicitly validate both node.func.id and node.func.attr. Allowed specific, required functions like Depends, depends, Field, PrivateAttr, Tag, and Parameter.
✅ Verification: Ran format, lint (mise //:format, mise //:check), and the test suite (uv run pytest tests/unit/ tests/di/ --no-cov) to ensure correct validation logic and no regressions.

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PR created automatically by Jules for task 4402007923819433601 started by @bashandbone

Summary by Sourcery

Restrict dynamic AST-evaluated type strings to a small whitelist of safe callable names to close an arbitrary code execution vulnerability in the DI container.

Bug Fixes:

• Block arbitrary function calls in AST-based type validation by only allowing specific whitelisted callables in TypeValidator.

Documentation:

• Document the newly fixed AST call-node vulnerability and its mitigation steps in the Sentinel security log.

[google-labs-jules]

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[sourcery-ai]

Reviewer's Guide

Restricts AST-based type string evaluation to a small, explicit set of safe callables to close an arbitrary code execution vulnerability, and documents the incident in the Sentinel security log.

Sequence diagram for restricted AST call validation in type evaluation

sequenceDiagram
    participant ClientCode
    participant ast
    participant TypeValidator

    ClientCode->>ast: parse(type_str, mode=eval)
    ast-->>ClientCode: ast.AST tree
    ClientCode->>TypeValidator: generic_visit(ast_tree)

    loop visit_nodes
        TypeValidator->>TypeValidator: generic_visit(node)
        alt node is ast.Call
            alt node.func is ast.Name and id in {Depends, depends, Field, PrivateAttr, Tag, Parameter}
                TypeValidator-->>TypeValidator: is_allowed = True
            else node.func is ast.Attribute and attr in {Depends, depends, Field, PrivateAttr, Tag, Parameter}
                TypeValidator-->>TypeValidator: is_allowed = True
            else forbidden callable
                TypeValidator-->>ClientCode: raise TypeError(Forbidden function call in type string.)
            end
        else non_call_node
            TypeValidator-->>TypeValidator: super().generic_visit(node)
        end
    end

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File-Level Changes

Change	Details	Files
Harden AST type validation by whitelisting allowed function calls and rejecting all other ast.Call nodes.	Extend TypeValidator.generic_visit to detect ast.Call nodes in parsed type strings. Introduce an explicit whitelist of allowed callable identifiers (Depends/depends, Field, PrivateAttr, Tag, Parameter). Validate both simple names (ast.Name.id) and attribute access (ast.Attribute.attr) against the whitelist before allowing a call node. Raise TypeError on any function call in a type string that is not in the whitelist, preventing execution of arbitrary callables.	src/codeweaver/core/di/container.py
Record the vulnerability and its remediation details in the Sentinel security documentation.	Add a dated Sentinel entry describing the AST-based arbitrary code execution vulnerability. Document the security learning around restricting ast.Call nodes and whitelisting callables. Describe preventative measures for future AST-based validation implementations.	.jules/sentinel.md

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[github-actions]

🤖 Hi @bashandbone, I've received your request, and I'm working on it now! You can track my progress in the logs for more details.

[github-actions]

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[sourcery-ai]

Hey - I've left some high level feedback:

• Consider extracting the allowed callable names into a single shared constant or set so that ast.Name and ast.Attribute checks don’t duplicate hardcoded string lists and are easier to maintain.
• You might want to make the error message include the attempted function name (where available) to aid debugging when a forbidden call is encountered, while still keeping it generic enough not to leak unnecessary details.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- Consider extracting the allowed callable names into a single shared constant or set so that `ast.Name` and `ast.Attribute` checks don’t duplicate hardcoded string lists and are easier to maintain.
- You might want to make the error message include the attempted function name (where available) to aid debugging when a forbidden call is encountered, while still keeping it generic enough not to leak unnecessary details.

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